Unless otherwise indicated herein, the approaches described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
An electric double-layer capacitor may utilize nano-structures to increase the effective surface areas of electrodes. The electric double-layer capacitor can be conventionally constructed either based on an activated carbon material used for the porous electrodes of the capacitor, or using carbon nano-tubes as the electrodes for the capacitor. The electrodes made out of the activated carbon material often may have insufficient surface areas. On the other hand, the adoption of carbon nano-tubes as electrodes may be limited by costs and technical deficiencies. For instance, it is technically difficult to massively and evenly grow the carbon nano-tubes on a wafer. Also, it may be hard for the electrolyte to infiltrate the highly dense carbon nano-tubes. Further, mass-producing the double-electrode capacitors in conventional approaches may incur high manufacturing costs.